This notebook reveals the total number of unique asof_dates for each and every Fundamental factor for all assets in the QTradableStocksUS universe. Window_size is set to 10, so we should expect 10 unique dates for factors that change daily, and 1 unique date for most factors that change less frequently. However, the results do not match expectations.

Listed here are all factors that are updated daily for every asset. Clearly, most all of these are all fixed and should never be updated. The daily asof_dates for fixed values creates uncertainty, as will be discussed in the next section.

Problems arise when we have daily asof_dates, yet cannot be sure if the values are supposed to change.

For AAPL we have daily asof_date for all the following factors. Clearly, many of these factors are only set one time, like 'cik'. Some, if they do change, we'd like to easily determine when they changed, like 'exchange_id'. But unfortunately the only way to know when any of these values changed is to scan the actual value for every date and detect changes in the values.

Even worse, values that might change daily must not only be guessed from the daily asof_dates, but also confirmed by checking that the actual values change daily as well. For instance, 'cf_yield' looks like it would update daily, but does it? We'd have to check that the actual values change. What if on some days the values change and others they do not? Does that mean the values are updated only occasionally?

To further illustrate the issue, we have here for AAPL a financial ratio determined from the quarterly balance sheet, but it is shown to be updated daily by its asof_dates. This raises the question of what happens with a stock split? I guess the asof_date would continue updating daily, but would the value reflect the stock split? Probably not, since this is a balance sheet ratio. But the why list it as having a daily asof_date.